Refrigeration



March 14, 1944. F; A. GROSSMAN ,3

REFRIGERATION Filed May 13, 1941 1 liquid columns.

"densate from'space l3.

Patented Mar. 14, 1944 2.344.245 aai'mdaas'rron Franklin A. Grossman,Evansville, Ind, assignor to Serve], Inc., New York, N. Y., acorporation of Delaware Application May 1:, 1941, Serial No. 393,160

Claims. (01. 62-5) This invention relates to refrigeration, and is moreparticularly concerned with non-conden sible gases that collect inrefrigeration system.

It is the object of this invention to provide an improvement forcontrolling removal of noncondensible gases from refrigeration systems.This is accomplished by providing a suitable vacuum pump to effectremoval of non-condensible gases from a refrigeration system,- andoperating the pump within a definite pressure range in the refrigerationsystem. 2

The above and other objects and advantages of the invention will bebetter understood from the following description taken in conjunctionwith the accompanying drawing forming a part of this specification, andof which the single flgure more or less diagrammatically illustrates arefrigeration system with which the invention is associated.

Referring to the drawin the present invention is embodied in atwo-pressure absorption refri 'eration system like that described inPatent No.

liquid with the liquid following along the inside walls of tubes It.

The water vapor flows upwardly through the tubes or risers it intovessel II which serves as a vapor separator. Due to baiiling in vessel I8, water vapor is separated from raised absorption solution and flowsthrough conduit 23 into condenser H. The condensate formed in condenserll flows through a U-tube 24 into a flash chamber 23 and from the latterthrough a conduit 23 into evaporator l2.

The evaporator l2 includes a plurality of horizontal banks of tubes 21disposed one above the other and to which are secured heat transfer flns23 to provide a relatively extensive heat transfer surface. The liquidflowing to evaporator-l2 is divided in any suitable manner for flowthrough the uppermost banks of tubes 21.

. The dividing of liquid may be effected by prowater passes throughsuccessively lower banks.

2,282,503 of A. R. Thomas and P. P. Anderson,

Jr., issued May 12, 1942. A system of this type operates at lowpressures and includes agenerator or vapor expeller Ill, a condenser ll,an evaporator l2, and an absorber It which are interconnected in suchamanner that the pressure differential in the system is maintained byThe disclosure in the aforementioned Thomas and Anderson application maybe considered as being incorporated in this application, and, ifdesired, reference may be had thereto for a detailed description of therefrigeration system. As

shown, the generator I. includes an outer shell 13- within which aredisposed a plurality of ver-- tical riser tubes l3 having the lower endsthereof communicating with a space 1 and the upper ends thereofextending into and above the bottom of a vessel It. The space l3 withinshell it forms a steam chamber about the tubes" It to which steam issupplied through a conduit 20.

The space I! provides for full length heating of tubes It. a vent 2|being formed at the upp r end of shell IS. A conduit 22 is connected tothe lower part of shell It for draining con- The system operates at apartial vacuum and -coritains a water solution of refrigerant inabsorbent liquid, such as, for example, a water solution of about 40%lithium chloride by weight. With steam beingsupplied through conduit 22to space I! at atmospheric pressure, heat is applied to. tubes l3whereby water vapor is expelled from solution. The absorption liquid israised by gas 01-. vapor-lift action with the e:- pelled water vaporforming a-central core within an upwardly rising annulus of the liquid.The expelled water vapor rise more rapidly than the viding a liquiddistributing trough 29 into which the liquid flows through the conduit23. The

. of tubes through suitable end connections which are open to permitescape of vapor from-the tubes, and any excess liquid is discharged fromthe lowermost bank of tubes 21.

The water supplied to tubes 21- evaporates therein to produce arefrigerating or cooling effectwith consequent absorption of heat fromthe surroundings, asfrom a stream of air flowing over the exteriorsurfaces of the tubes 21 and fins 23. The vapor formed in tubes '28passes out into end headers 30 which are' connected at their lower endsto absorber i4. chamber 25 is provided to take care of any vaporflashing of liquid beingded to evaporator 12 through U-tube 24. Theflashed vapor formed in the initial cooling of the liquid flowing fromcondenser H passes through a conduit 3| into one of the headers 30 andmixes with vapor formed in the evaporator I 2, so that disturbances inthe evaporator. due to vapor flashing are avoided. Y

In absorber ll refrigerant vapor is absorbed into concentratedabsorption liquid which enters through a conduit 32. The enteringabsorption liquid 'flows into a vessel 33 in which liquid is distributedlaterally or cross-wise of a plurality of vertically disposed pipebanks34 which are arranged-along side of each other. The liquid flows fromvessel 33 through conduits 35 into a plurality of liquid holders anddistributors 33 The-"water vapor formed in evaporator I 2 passes throughthe headers into theabsorber H where it is absorbed by the absorptionliquid and, due to such absorption of water vapor, the

absorption liquid is diluted, The-diluted absorp- During operation-oithe refrigeration system, i I

tion liquid flows through "a conduit 31, a first p'as-' sage in liquidheat exchanger 38, conduit 39, vessel and conduit 4| into the lowerspace ll of v generator l0. Water vapor is expelled out of solution ingenerator ill by heating, and the solution is raised by gas orvapor-lift actionin riser tubes l5. as explained above;

The absorption liquid in vessel l8 is concennon-condensible gases maycollect therein, and in condenser II the non-condensible gases areconcentrated in the dead-end or'bottom part due to the sweeping actionof theinflowing vapor. To

remove non-condensible gases {110m condenser II to absorber I4 .in thelow pressureside ot'the system a liquid siphon trap is provided inconduit 24, as described in an applicationoi Philip P. Anderson,Jr.,Serial No. 350,883, filed August 3, 1940.- The siphon trap." may beof any desired -s hap e and. is shown ii! the form of a complete tratedsince water vapor has been expelled therefrom in generator Hi. Thisconcentrated absorption liquid flows through a conduit 4-2, asecondpassage in liquid heat exchanger 38, and conduit 32 into the upperpart of absorber 14. This cir culation of absorption liquid results fromthe raising of liquid by-vapor-liit action invertical riser tubesl6,whereby the liquid can flow to ab sorber I 4 and retum'irom thelatter to 'thegenerator III by force of gravity;

The vessel 40 is cylindrical in shape and disposed about shell-15 ofgenerator" l0. By arranging vessel 40 to receive heat derived ironi thesteam in'space lsjpreheating' of absorption'liquid flowingto generatorIII is effected. The upper 1 ends 01' the pipe banks 34 through aconduit 44 and leaves the upper ends of the pipebanks 34 through aconduit 45. The conduit 45 is connected to condenser il wherebythe samecooling medium may be utilized to cool both condenser and absorber l4,and from condenser II the cooling medium flows through a conduit 46 towaste.

The system operates at low pressures with the generator 10 and condenserll operating at one pressure and the evaporator l2 and absorber l4operating at a lower pressure, the pressure difierential therebetweenbeing maintained by liquid columns.

Thus, the liquid column formed in tube 24 'main tains the pressurediilerential between condenser II and evaporator l2, the liquid columnin conduit 31 maintains the pressure diilerential between the outlet ofabsorber l4 and generator 10, and the liquid column formed in conduit 32and connected parts including conduit 42 maintains the pressuredifferential between the inlet of the absorber and the upper part ofgenerator circular loop'in the down-legoi U-tube 24.

The liquid formed in condenser Ii flows into When the circular loop iscompletely filled, with liquid to the level p, the liquid is siphonedfrom the loop into the down-leg of U- tube' 24. The gas inthedo'wn-legof U-tube 24, between the loop'4l and liquid level 2, istrapped by the liquid siphoned from the loop. Imme diately after liquidhas. siphoned from the loop.

' gas passes from the bottom-part of condenser through the loop-41' intothe "down-leg of U- tube 24. When liquid flowing from condenser it againreaches the level pin the circular loop 41, liquid is againsiphonedin'to the down-leg oi the tube 24. In this manner gas passingfrom condenser I l into the down-leg oi-tube 24, before the liquid sealis formed in loop 41, is segregated by the'liquid subsequently siphonedinto the'dowm leg of the tube. T I Y The gas segregated between thesuccessive bodies 01 liquidsiphoned-from. loop 41 is compressed by thesiphoned liquid and passes through the U-tube by the gravity flow ofliquid from condenser II to evaporator l2. In this waynoncondensi'ble'gases collecting in the upper part of 1 generator Iilandcondenser II are removed or transferred from these parts of the systemto the evaporator 12 and absorber l4 to which is connected a vacuum pump48 for removing non-condensibl'e gases from the refrigeration system.

The vacuum pump 48 is provided to'remove non-condensible gases from thelow pressure side of the refrigeration system through a' conduit 49,-

vessel 50 and conduit 5|. The conduit'5l extends into the lower part ofabsorber H to which region the non-condensible gases are swept by thehigh velocity'wat'er vapor flowing into the absorber from evaporator l2.

The vacuum pump 48 is operated by an electric motor 52 which isconnected through'conductors as between the arms of a U-shaped member59.

Hi. 'In operation, the liquid columns may form in conduits 31, 42- anddown-leg of tube 24 to the levels 0:, y and z, for example. The conduitsare of such'size that restriction to gas flow is efi'ected withoutappreciably restricting flow of liquid.

, The liquid column formed in vessel 40 and cone duit 4| provides theliquid reaction head for raising liquid in riser tubes I6 by vapor-liftaction. The vessel 40 is of suiflcient volumeto hold the liquiddifferential in the system and is of such cross-sectional area that theliquid level therein does not appreciably vary, so that a substantiallyconstant reaction head is provided for lif ing iq uid in generator III.

, or right hand arm 01' the manometer SI.

The switch 51 formspart of a lever which serves as an armature elementadapted to be raised and attracted toward a relay coil 60 when thelatter is energized. With raising of switch 51 the con tacts'therein arebridged by a body of mercury to complete the electric circuit for motor52. It is recommended that switch 51 be of the typ provided with a damor restriction, as shown in the drawing, for delaying the flow ofmercury. This prevents chattering of the control switches when themercury in the manometer is floating at acontrolpoint.

The coil 60 is connected in conductor 56 which is connected in the lefthand arm of a manometer 6|. The conductor 55 is connected in the closedThe manometer contains a suitable liquid, such as, for example, mercuryor the like, and is connected by assent a tube 62 to the upper part ofthe absorber. When the pressurevprevailing in theabsorber I4 is suchthat the memury contained in the manometer simultaneously contactsconductors 55 and 56. an electric circuit is completed for coll l6 toeffect closing of switch 51. A manual switch 63 isconnected betweenconductors 55 and 66 across the Y manometer 6 I, so that a circuit canbe completed The relay I6 is operatively connected to an ex-' pansibleand contractible bellows 1| which in turn is connected by a tube 12 tovessel 56. When the pressure in vessel 56 becomes sufllciently. low, thebellows H contracts to move the arm of relay l8 downward to open thecircuit for coil 61 of solenoid valve 64. A spring I3 cooperateswith'bellows TI to insure opening of relay 10 when the pressure withinthe bellows falls to a predetermined low value.

, A suitable check valve 14 is provided in conduit are adjusted toeflectbpening of valv member 86 only after the pressure in vessel hasbeen reduced to a very low value and preferably at or below 9mm. Hg.

When substantially all of the objectionable noncondensible gases havebeen removed from the rei'rigeration system to lower the pressure inabsomber [4 to a sufllciently low value sothat the mercury column in theright-hand. arm oi manometer 6i no longer contacts conductor 55,- thecircuit for coil 80 is opened and switch 51 falls to its lower openposition. This permits the mercury inthe switch to flow by gravitytoward the left-hand end ofthe bulb to open the contacts therein anddisconnect motor 52 from the source f of electrical supply. With motor52 no longer energized and vacuum pump 48 no longer operating, thepressure in conduit 48 increases to atmospheric pressure. When thevacuum pump 48' ceases operating, however, the check valve 14 imphericair from entering vessel 50 through con duit 46. In the event oi. faultyoperation of check 5 0 and conduit 5| when the motor 52 is disconnectedfrom the source of electrical supply and the vacuum pump 48 is renderedinoperative.

.In .the kind-of refrigeration system described above, the normaloperating pressure desired to be maintained in absorber l4 may be in theneighborhood of 9 mm. Hg. In this case the conductor 55 is located atsuch a position at the closed or right-hand arm of manometer 6| that,when the pressure in absorber l4 tends to increase above 9 mm. Hz, themercury column in the right-hand arm contacts conductor, 55. 'Theconductor 56 is located at such a position at the left-hand arm that,when the pressure in absorber l4 tends to rise above 9 mm. Hg, thisconductor is also contacted by mercury. With the mercury in manometer 6|simultaneously contacting conductors 55 and 56, the electric circuit forcoil 60 is comvvalve 14 with resultant rise in pressure in vessel 50,the bellows 'II- will expand against the action of spring 13 to closerelay 10 and complete the electric circuit for coil 61. When this occursplunger 66 is raised within coil 61 against the force of gravity toeffect closing of valve member 65.

The conductor 56 preferably is located-at such a height in the left-handarm of manometer 6| that, when the pressure in absorber l4 exceeds apredetermined value, the mercury in the lefthand column will be belowthe position of conductor 56. In such case, of course, the conductor 56will not be contacted by mercury and the circult for coil '60 will beopened. Under these conditions switch 51 opens to disconnect motor 52pleted whereby switch 51 is attracted an raised duit 49 and vessel 50 iswithdrawn therefrom and discharged into the atmosphere. v When thepressure in vessel 50 reaches a predetermined low value due to operationof vacuum pump 48, the bellows II contracts sufliciently to from thesource of electrical supply and vacuum pump 48 becomes inoperative toeffect withdrawal of non-condensi'ble gases from the refrigerationsystem. I

In a refrigeration system of the character referred to above in whichthe pressure in absorber l4 normally is about 9 mm. Hg, the conductor56- may be connected in the'left-hand arm of manometer 6| at such aposition thatthe circuit for 'coil 60 will be opened ,whenthe absorberpressure exceeds 16 mm. Hg, for example. This is the pressure that mayprevail in absorber l4 when the refrigeration system is shut down witlrno steam being supplied through conduit 20, and with evaporator l2 at atemperature of F. or higher.

This is particularly true when the evaporator I2 is positioned in thesame air duct as a heater which is used for heating air during theperiods of th year when the refrigeration system is not'beopen relay 10.The spring 13 cooperates inthe opening of relay 10 whereby the circuitfor coil-6'! of solenoid valve 64 i opened. With deenergization of coil61 valve member 65 no longer will be held in its upper position byelectromagnetic attraction and will move downward to its open positionby gravity action. The opening of valve member 65 renders vacuum pump 48effectiveto withdraw non-condensible gases from absorber l4 and todischarge such gases to the atmosphere;

Since it has been assumed above that operation of vacuum pump 48 isstarted when the pressure in absorber l4 tends to rise approximatelyabove 9 mm. Hg, it will be understood that under these conditions relayI6 and its associated bellows ll ing operated. Th pressure in evaporatorl2 and absorber l4 may be in a range from 16 to 22 mm. Hg for acorresponding air temperature range from 65 to F.

Hence, when the refrigeration system is shut down and an associatedheater is operating to gases from the system. Moreover. the control"provided iswof such a character thatit is completely automatic and maybeemployed with a heating systemwhich, together .with the refriger- Iation system described, provides for year round conditioningof air.While a single embodiment of the invention has been shown and described,it will be pparent to-those' skilled in the artthat variousmodifications and changes may be-made-without departof'a refrigerant andan absorption solution, means for. translerring non-condensible gasesfrom a part of the system at one pressure toanother part of the systemat a different pressure, a vacuum pump connected to said other part forremovin non-condensible gases. from the system, and

means responsive topressure in said other part for causing operation ofsaid vacuum pump when the pressure in said other part i within apredetermined range and stopping said operation when the pressure isbelow or above said range.

2. In refrigeration apparatus of the absorption type having a pluralityof interconnected parts to form a system for circulation of arefrigerant and an absorption solution and in which noncondensi-blegases may collect, a vacuum device. connected to one of said parts forremoving noncondensible gases from the system, means respon sive to riseof pressure in the system to a predetermined value for rendering saiddevice operative .and responsive to an additional increase in pressurein the system to a second predetermined value for rendering said deviceinoperative.

3. In refrigeration apparatus of the absorption type having a pluralityof interconnected parts to form a system for circulation of arefrigerant and an absorption solution and in which non-condensiblegases may collect, a vacuum device and aconnection therefrom to a partof said system for exhausting non-condensible gases therefrom, a valvein said connection, and structureresponsive to increase of pressure insaid part to a predetermined value for rendering said device operative,said structure being so constructed and arranged that said valve iscaused to open 'afterthe pressure in said connection between said valveand said device has been reduced to a definite low. value due tooperation of said device.

4,. In refrigeration apparatus of theabsorption type having a pluralityof interconnected parts to form a system for circulation of arefrigerant and an absorption solutionand in which noncondensibl gasesmay collect, a vacuum device and a connection therefrom to a partof saidsystem, structure responsive toincrease in'pressure in said part to apredetermined value for rendering said vacuum device operative, andselfoperating, valve meansin said connection constructed and arranged toopen with operation of said vacuum device and to close and shut off thesystem from atmosphere when said device is rendered inoperative by saidstructure.

5. In a refrigeration system subject to'the appearance ofnon-condensible gases therein, a device" connected to said system forwithdrawing such gases, anda control device operative responsive to apressure condition within the system to control. operation of said gaswithdrawing device so that the latteroperateswhen the pressurewithin-the system. is within a predetermined range, butfis inoperativewhen the pressure within the sy'stemfisf below or above such range.

6. The combination asin claim 5 in which said control device is,eleetrically' actuated and includes a manometer containing anelectrically conductive liquid, said manometer being connected to saidsystem so as to sense the pressure therein and havingelectricalcontacts,one in each leg and atdiflerent elevations. I

"7. An .absorption refrigeration system subject to appearance therein ofnon-condensible gases,

in the path through which said gases are swept,

and a control deviceoperative responsive to pressure in said system forrendering said gas withdrawing device operative within a certain rangeof pressures, and inoperative both above and below said range.

vacuum producer operative within a certain range of pressures in saidsystem, and inoperative both above and below said range.

9. An absorption type refrigeration system emplaying water as arefrigerant which is evaporated under vacuum conditions, said systembeing subject to appearance of non-condensible gases therein, a vacuumpump connected to said system and operative to withdraw said gases, acontrol device for controlling operation of said pump, said controldevice including an electric switch type manometer subjected to internalpressure in said system, and a relay, said manometric switch beingconstructed and arranged to energize said relay within a certainpressure range, and deenergize said relay both above .and below saidrange, and said relay being operative to cause operation of said pumpwhen energized.

10. In a refrigeration apparatus of the absorption type having aplurality of parts including a generator, a condenser, an evaporator,"and an absorber interconnected to form a system for circulation of arefrigerant and an absorption solution and in which non-condensiblegases may accumulate, a vacuum device connected to the system forexhausting non-condensible gases therefrom, and a control meansresponsive to an increase in pressure in therefri'geration system forrendering said vacuum device operative and responsive'to a furtherincrease in pressure corresponding to a temperaturein the evaporator

